Partial alkali-metal ion extraction from K_(0.8)(Li_(0.27)Ti_(1.73))O_4 using PTFE as an extraction reagent

摘要

The alkali-metal ion extraction ability of an inert material, polytetrafluoroethylene (PTFE; empirical formula CF_2), was clarified by characterizing a partially alkali-metal ion-extracted layered compound, K_(0.8)(Li_(0.27)Ti_(1.73))O_4. Washing K_(0.8)(Li_(0.27)Ti_(1.73))O_4 in water extracts only 44% of the interlayer K~+ and no intralayer Li~+; on the other hand, 53% of the interlayer K~+ and approximately 10% of the intralayer Li~+ ions were extracted from K_(0.8)(Li__(0.27)Ti_(1.73))O_4 by the reaction with PTFE at 350 °C under flowing Ar. A systematic decrease in the lattice parameters a and c along the intralayer directions and an increase in b along the interlayer direction were observed, consistent with the alkali-metal ion deintercalation amount as a function of the reaction temperatures and the reacted PTFE amounts. After the reaction with K_(0.8)(Li_(0.27)Ti_(1.73))O_4: CF_2 = 1: 0.6 in mol, the lattice parameter b increased to 1.5607(3) nm from 1.5522(2) of the pristine K_(0.8)(Li_(0.27)Ti_(1.73))O_4, and this change in the lattice parameter was approximately one order of magnitude larger than those in a and c.